Data prefetching, or early fetching of data into a cache, is a feature implemented in a processor to augment a probability of having needed data in a timely manner and so, maintain a high processing efficiency. When the data is available at a first cache level, a number of cycles when the processor stalls, for example, because of waiting for data to come back from farther cache levels or memory, may be reduced. Many typical prefetch units use fixed parameters for prefetch operations.